When shoppers met the smartphone, they quickly learned that the device was ideal for shopping around — while shopping in person. They could do things like check Kelley Blue Book prices at car dealerships, or see if a dress in a store was being sold for less at the shop down the street—or online.

More than half of Americans now own smartphones, and it’s this practice of “showrooming”—touching and feeling merchandise in stores before consulting the smartphone for a better deal—that seems to have most changed how consumers shop lately.

But there are other, quirkier and somewhat unexpected ways that smartphones are affecting the retail scene. Here are three:

Fewer Impulse Purchases in Checkout Lines
The people waiting in a store checkout line are considered a captive audience—one that might be tempted into buying candy, soda, celeb magazines, and any number of goods, without thinking much of it. But smartphones seem to be more interesting than the magazine cover featuring Kim Kardashian’s latest antics. Single sale copies of magazines, largely purchased while waiting in line at the grocery store, are down 8.2% from last year. Sales of gum have taken a hit, too, declining 5.5% last year. Evidently, instead of amusing ourselves examining new gum flavors, we’re checking our emails or playing Angry Birds.

More Shopping Collisions
In my research, I speak with lots of consumers, including Brett, who has been a weekly regular at San Francisco’s popular Saturday morning farmers market since it opened. Not anymore, though. “It’s always been crowded but now it’s impossible,” Brett told me. “Everyone’s looking down at their phone, blocking passageways, walking right into you sometimes. It’s rude.”

Another shopper named Julie feels the same way about shopping at Ross. “I was trying to make my way around this rack and there’s this girl just texting away, oblivious,” she said. It’s not just consumers who tell me there’s an epidemic of smartphone-distracted shoppers out there, some who obliviously bump into strangers while staring at their screens. According to Sara, a sales associate in a department store, “My customers are always on their phones. Not necessarily showrooming, but they’re not just shopping either. They’re multi-tasking.” And in the meantime, they’re using up the time of a sales staffer who might otherwise be helping another customer.

More Salesperson Snubs
On second thought, perhaps there aren’t many customers waiting for assistance inside stores. Not if they have smartphones anyway. A study by Accenture found that 73% of shoppers with smartphones would rather consult their devices than a salesperson for looking up information quickly. The study was conducted a few years ago, and presumably since then, shoppers have only grown more comfortable turning to their smartphones over salespeople.

And why do consumers like Patty prefer the smartphone to a living, breathing human being? “It’s faster,” she said, simply. Tony, a young Apple fan, explained to me that he likes to figure things out for himself. “I don’t want to talk about it,” he said. “I just want to see how things work. I like the lists that compare product specs, and then I can see it in action.”

Another upside to smartphones: Unlike many store sales associates, they don’t work on commission. A smartphone probably isn’t going to try to upsell you on something of dubious value. And if a site or app tries to do so, you can always turn to a different one. You can also just turn the device off.

Kit Yarrow chairs the psychology department of Golden Gate University and was named the university’s 2012 Outstanding Scholar for her research in consumer behavior. She is a co-author of Gen BuYand is a frequent speaker on topics related to consumer psychology and Generation Y